Wire thread insert with redress mounting tang as well as its manufacturing and installation

ABSTRACT

A wire thread insert comprises besides a cylindrical helix consisting of a plurality of coils a moving tang projecting into the interior of the helix for installing the wire thread insert into a receiving thread. The wire thread insert is connected to the cylindrical helix via a bending portion such that the moving tang can be redressed into the receiving thread after installation of the wire thread insert. The wire thread insert is installed by means of an installation tool with a mounting spindle, which installs the wire thread insert in the receiving thread via a moving shoulder and the moving tang. A compression blade provided at the mounting spindle bends the moving tang back into the receiving thread while the mounting spindle is removed from the installed wire thread insert.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/884,225 filed Jul. 11, 2013 which is a national phase ofPCT/EP2011/068962 filed Oct. 28, 2011 and claims the priority of Germanpatent application DE 102010050735.0, filed on Nov. 8, 2010. The entirecontents of these priority applications are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a wire thread insert formounting/installing in a receiving thread of a component, a componenthaving a receiving thread in which the wire thread insert is arranged,an installation tool for this wire thread insert, an installation methodof this wire thread insert in the component having a receiving thread, amanufacturing method for this wire thread insert as well as a device formanufacturing this wire thread insert.

BACKGROUND

Several wire thread inserts for mounting in a receiving thread of acomponent are known in the prior art. They are for example described inU.S. Pat. No. 2,363,789, EP-A-0 140 812 and EP-A-0 157 715. Regularly,the outer diameter of the cylindrical walls of the wire thread inserthas to be chosen slightly greater than the outer diameter of thereceiving thread of the component. Therefore, mounting of the wirethread insert into the receiving thread of the component has to takeplace involving a diameter reduction of the wire thread insert. In thisway it is ensured that due to the elastic re-deformation of the wirethread insert after installation into the receiving thread a tight fitof the wire thread insert is achieved.

A half coil at the end of the cylindrical helix of the wire threadinsert is retracted radially inwardly in the known way (EP-B1-0 228 981)to facilitate the screwing-in of the wire thread insert into thereceiving thread. The smallest outer diameter of the retracted sectionof the wire thread insert should approximately be equal to or slightlygreater than the corresponding outer diameter of the receiving thread inthe component. Further, the wire cross-section of this known wire threadinsert is tapered at the end to facilitate the screwing-in of the wirethread insert into the receiving thread and to avoid damages at thethread bore in the component.

Different embodiments of wire thread inserts are also disclosed inEP-B1-0 983 445. Thereto belongs for example the wire thread insert 1shown in FIG. 1 consisting of a cylindrical helix 2 having a pluralityof helically wound coils 3. A first coil 4 of this cylindrical helix 2leads to a mounting tang/installation tang 6 projecting radiallystraight into the cylindrical helix 2. The mounting tang 6 is gripped bymeans of a suitable installation tool and the wire thread insert 1 isscrewed into the receiving thread of the component therewith. Themounting tang 6 is removed after completion of the installation as themounting tang 6 is broken off by means of the predetermined breakingpoint 5 in the first coil 4. In this way, a receiving thread is formedhaving a continuous screw-mountable wire thread insert.

In this construction of the wire thread insert 1 it is especially adisadvantage that the mounting tang 6 has to be broken and removed. Atthe automatic installation of such wire thread inserts 1 it may even benecessary to record the broken and removed mounting tang 6. It isfurthermore disadvantageous that the wire thread insert has to bemounted into the receiving thread of the component in a certainorientation. This is because the wire thread insert 1 has to bescrewed-in into the receiving thread with the mounting tang 6 ahead.

A further wire thread insert 1 which is known from the prior art isshown in FIG. 2. In contrast to the wire thread insert of FIG. 1, thewire thread insert of FIG. 2 does not comprise a mounting tang. Instead,a moving groove 7 is provided in the first coil 4 of the wire threadinsert. An installation tool of the wire thread insert engages thismoving groove 7 to screw the wire thread insert 1 into the receivingthread of the component. The free end of the first coil 4 of the wirethread insert 1 is provided with a tapering 8 to support this screw-inprocess and also the entering of the wire thread insert 1 into thereceiving thread. The construction of the wire thread insert 1 accordingto FIG. 2 permits only a very sophisticated automated mounting into thereceiving thread of the component. The wire thread insert 1 is insertedby means of a preload cartridge at an automated assembly. The insertionrequires an excessive monitoring of the process. Further, the wirethread insert 1 of FIG. 2 can be reduced in its diameter during theinstallation only restrictedly so that the wire thread insert 1 applieslower holding forces after the installation in the receiving thread tookplace compared to for example the wire thread insert 1 of FIG. 1.

Starting from the wire thread inserts of the prior art, the object ofthe present invention is providing a wire thread insert which isinstallable into a receiving thread of a component with lesser effortand more process reliable compared to the prior art. It is a furtherobject of the present invention to provide a respective installationmethod, an installation tool, a manufacturing method and a manufacturingdevice for such a wire thread insert.

SUMMARY

The above mentioned technical problems are solved by a wire threadinsert according to the independent patent claim 1, a component having areceiving thread in which this wire thread insert is installed accordingto the independent patent claim 6, an installation tool for such a wirethread insert according to the independent patent claim 7, aninstallation method for this wire thread insert according to theindependent patent claim 13, a manufacturing method for this wire threadinsert according to the independent patent claim 17 as well as by adevice for manufacturing this wire thread insert according to theindependent patent claim 21. Advantageous embodiments and furtherdevelopments of the present invention are derivable from the presentdescription, the figures as well as the appending claims.

The inventive wire thread insert for mounting/installing in a receivingthread of a component comprises the following features: a cylindricalhelix having a plurality of helically wound coils of a wire, the helixhaving a first and a second end, wherein a first coil provided at thefirst end has a moving tang projecting into an interior of the helix viaa bending portion and the moving tang is inseparably, i.e. notremovable, connected to the first coil and redressable from the interiorof the helix via the bending portion.

The present invention provides a wire thread insert which isadvantageously installable in the receiving thread of a component viaits moving tang. This moving tang enables applying a sufficient hightorque as well as the desired diameter reduction of the wire threadinsert to facilitate the installation of the wire thread insert in thereceiving thread. In contrast to the prior art, the moving tang has notto be removed from the wire thread insert. Instead, the moving tang isbent back, bent down, bent over or redressed, respectively, into thepathway of the first coil via the bending portion and thus, also intothe receiving thread of the component. For this purpose, the wire threadinsert with bending portion and moving tang is formed such that thebending portion allows a redressing of the moving tang without breakingthereby. Further, the moving tang is connected to the wire thread insertvia the bending portion in a sufficient stable way so that a screwing inof the wire thread insert into the receiving thread of the component isnot affected.

The present invention is further preferably characterised in that themoving tang is redressable permanently into the receiving thread of thecomponent. This redressing of the moving tang is realised by means ofthe installation tool of the wire thread insert. An elastic resetting ofthe moving tang into the interior of the helix of the wire thread insertis prevented during the redressing of the moving tang. This ensures thatthe moving tang can be bent radially outwardly into the receiving threadof the component over and above the envelope shape of a screw later tobe inserted into the receiving thread or the envelope shape of a threadplug gauge and can stay there. Thereby it is guaranteed that a screw-inmoment of a screw in the receiving thread of the component is onlynegligibly affected and an accuracy to gauge of the wire thread insertwithin the receiving thread of the component is ensured.

Thus, it is preferred to provide the moving tang of the wire threadinsert in the shape of a circular arc whose tang radius is equal to aradius of the first coil of the cylindrical helix. By means of thisshaping it is ensured that the redressable moving tang resumes the firstcoil of the cylindrical helix.

It is further preferred that the moving tang has a continuous front endcompression face at its free end, which is arranged within the radialplane of the helix in an angle of 90° to 60° related to the longitudinalaxis of the wire.

The moving tang is redressed radially into the receiving thread of thecomponent during the assembly of the wire thread insert. Additionally,it is preferred to impinge the moving tang via the mentioned compressionface with a compression force, preferably tangential to the longitudinalaxis of the wire, so that a mechanical tension superposition resultswithin the bending portion of the wire thread insert. Consequently, themoving tang is compressed into the first coil of the cylindrical helixof the wire thread insert during the redressing via the compressionface. This compression ensures a permanent redressing of the moving tangso that the moving tang does not or negligible low spring backelastically into the interior of the cylindrical helix. In this way, themoving tang may be bent and/or calibrated radially outwardly permanentlyover and above the envelope shape of a screw to be inserted into thereceiving thread and a thread plug gauge.

According to another preferred embodiment of the inventive wire threadinsert, the wire in the bending portion between the first coil and themoving tang is modified mechanically, geometrically, thermally,chemically, in another way or not at all compared to the wire of thefirst coil so that a redressing of the moving tang is facilitated. Inthis context, it is for example preferred to provide the bending portionwith a redressing groove. This redressing groove leads in a geometricalway to a reduction of the material resistance in the bending portionduring the redressing of the moving tang. In a further embodiment, thebending portion is heated to reduce the strength of the wire in thebending portion and thus to improve the bending properties of thebending portion. Hence, all methods are appropriate which reduce theyield strength of the wire in the bending portion in such a way that aredressing of the moving tang is supported.

The present invention comprises also a component having a receivingthread, in which a wire thread insert according to one of the abovementioned embodiments is arranged.

Further, the present invention discloses an installation tool for theabove described wire thread insert in a receiving thread of a component,the tool having the following features: a rotatable mounting spindlewith a drive end for rotating the mounting spindle and a functional endfor installing the wire thread insert, wherein the functional endcomprises a moving shoulder by means of which the wire thread insert isscrewable into the receiving thread via the moving tang and acompression blade having a face by means of which the moving tang of thewire thread insert is redressable.

The inventive rotatable mounting spindle is constructed with itsfunctional end such that on the one hand the wire thread insert is easyinstallable in the receiving thread of the component via the movingtang. On the other hand, the compression blade of the functional end ofthe mounting spindle serves to redress the moving tang permanently fromthe cylindrical helix of the wire thread insert. Thereby, the necessityof breaking-off the moving tang and obstructions connected therewithduring an automated installation are omitted.

It is preferred that the compression blade and its face extend in radialdirection related to the mounting spindle and project over and above anouter diameter of the mounting spindle so that the moving tang ispermanently redressable into the receiving thread of the component. Thiscompression blade engages the already above described front endcompression face of the moving tang while rotating the mounting spindlecontrary to the screw-in direction of the wire thread insert into thereceiving thread. The compression blade compresses the moving tang sothat elastic reset forces of the moving tang, especially of the bendingportion, into the interior of the cylindrical helix are almost nullifiedand the moving tang remains in the receiving thread of the component.

The functional end of the installation tool comprises according toanother preferred embodiment a redressing shoulder by means of which themoving tang during the rotation of the mounting spindle is radiallyoutwardly movable and in combination with the compression bladeredressable. It is further preferred that the mounting spindle has anouter diameter at the functional end so that the wire thread insert maybe spindled or slipped on the mounting spindle. According to anotherembodiment of the installation tool, its compression blade is arrangedradially and/or axially moveable related to the mounting spindle toengage or disengage the moving tang.

The present invention further discloses an installation method of a wirethread insert having a redressable moving tang by means of aninstallation tool into a receiving thread of a component, the methodcomprising the following steps:

Spindling or slipping the wire thread insert on a functional end of amounting spindle of the installation tool, screwing-in of the wirethread insert into the receiving thread by rotating the mounting spindlein a first rotational direction, redressing/bending back the moving tanginto the receiving thread by rotating the mounting spindle in a secondrotational direction and spindling off or removing the mounting spindlefrom the wire thread insert with redressed moving tang.

For screwing-in the wire thread insert into the receiving thread, themoving tang of the wire thread insert preferably locks itself at amoving shoulder of the functional end of the mounting spindle so thatthe wire thread insert is rotatable by the mounting spindle. The movingshoulder at the functional end of the mounting spindle ensures in thisway that a sufficient high torque is generated for installation of thewire thread insert in the receiving thread. A radial bending-up of themoving tang occurs preferably by a bending-up shoulder at the functionalend of the mounting spindle to redress the moving tang into thereceiving thread. The radial bending-up occurs within a radial plane ofthe cylindrical helix of the wire thread insert, wherein the moving tangis radially outwardly bent up by the bending-up shoulder.

The present invention discloses further a manufacturing method of theabove described wire thread insert with redressable moving tang. Thismanufacturing method comprises the following steps: providing a wirehaving an circular arc shaped curved free end, locking the circular arcshaped curved free end at a front end of a winding spindle and windingthe wire onto the winding spindle so that a cylindrical helix ismanufactured having a plurality of helically wound coils of the wirewith a curved moving tang arranged inwardly related to the helix, andcutting-off the wound wire thread insert so that a further wire having asemicircular wound free end is manufactured.

A known wire for wire thread inserts is fixed at the winding spindlewith a circular arc shaped free end. Preferably, the circular arc of thecurved end extends over an arc angle of 10° to 180°, preferably 30° to120°, starting in the bending portion to the free end of the movingtang. The front end of the winding spindle is adapted such that despitethe locking and the subsequent winding of the wire, a curved moving tangis manufactured at the front end of the wire thread insert, which isarranged in the interior of the cylindrical helix. This moving tang isnot shaped straight radially inwardly related to the interior of thecylindrical helix of the wire thread insert compared to known movingtangs. Further, the first coil of the cylindrical helix has nopredetermined breaking point or groove, respectively, via which themoving tang could be removed afterwards.

According to a preferred embodiment of the manufacturing method, anunwinding of the wire thread insert from the winding spindle and atilting of the wire thread insert related to its longitudinal axiscompared to the longitudinal axis of the winding spindle occurs beforecutting-off. This course of action ensures that the cutting-off of thewound wire thread insert is subsequently realisable by a shear procedurewith at least one blade, preferably a first and a second blade. Comparedto known methods, the wire of the wire thread insert is not pinched-off,but instead is sheared-off or cut-off, respectively. This cutting-offcreates a continuous front end compression face at the free end of themoving tang, as described above.

According to another optional embodiment of the inventive manufacturingmethod, a modification of the wire in the bending portion takes placebetween the first coil of the wire thread insert and the moving tangmechanically, geometrically, thermally, chemically or in another waycompared to the wire in the first coil, so that the redressing of themoving tang is facilitated. By means of mechanical, geometrical,thermal, chemical or other conceivable methods, the strength and/oryield strength of the wire in the bending portion of the wire threadinsert is reduced. This ensures a redressing of the moving tang from theinterior of the cylindrical helix of the wire thread insert by means ofa lower force compared to a bending portion which was not modified. Ageometrical modification comprises for example a tapering of the wire inthe bending portion while a thermal modification by heating the wire inthe bending portion may reduce its yield strength and/or strength. Withthe same purpose and the same function, mechanical, chemical or othermodifications of the wire in the bending portion are applicable solelyor in combination.

Further, the present invention discloses a device for manufacturing theabove described wire thread insert, which has the following features: awire supply for a wire to be wound and a rotatably arranged windingspindle having a front end locking construction for the wire to be woundand a cutting construction with at least a first blade by means of whichthe wire of the wound wire thread insert is removable via a shearprocedure. It is preferred to provide the device for manufacturing thewire thread insert with a pointing assembly. By means of this pointingassembly, the wire of the bending portion between the first coil of thewire thread insert and the moving tang is modified mechanically,geometrically, thermally, chemically or in another way compared to thewire of the remaining wire thread insert to facilitate a redressing ofthe moving tang. Such a pointing assembly comprises for example amechanical assembly to generate a groove, preferably a round or angulargroove or a tapering in the wire of the bending portion. According toanother embodiment, the device for manufacturing the wire thread insertcomprises a thermal pointing assembly which heats the wire of thebending portion by means of electrical induction, by means of a laser orany other suitable heat source so that the material of the wire in thebending portion is modified such that a later redressing of the movingtang from the interior of the cylindrical helix of the wire threadinsert is supported or facilitated, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described with reference to theaccompanying drawings in more detail. It shows:

FIG. 1 a wire thread insert according to the prior art having a movingtang projecting radially inwardly and a predetermined breaking point forbreaking off the moving tang,

FIG. 2 a wire thread insert of the prior art having a moving groove atthe free end of the wire thread insert,

FIG. 3 a preferred embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 4 the wire thread insert of FIG. 3 with redressed moving tang,

FIG. 5A a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 5B the embodiment of FIG. 5A with a depiction of the tang bendingradius,

FIG. 6 the wire thread insert of FIG. 5 with redressed moving tang,

FIG. 7 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 8 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 9 a schematic depiction of a preferred embodiment of the mountingspindle of the installation tool with a wire thread insert withredressable mounting tang placed thereon,

FIG. 10 a schematic depiction of a preferred construction of thefunctional end of the mounting spindle,

FIG. 11 a schematic depiction of a preferred sequence during theinstallation of the inventive wire thread insert,

FIG. 12 a depiction of a preferred further sequence during theinstallation of the inventive wire thread insert,

FIG. 13 a flowchart of the preferred installation method for the wirethread insert with redressable moving tang,

FIG. 14 a schematic depiction of the preferred device for manufacturingthe wire thread insert with redressable moving tang,

FIG. 15 a flowchart of a preferred manufacturing method of the wirethread insert with redressable moving tang,

FIG. 16 a schematic depiction of a preferred construction of thefunctional end of the mounting spindle,

FIG. 17 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 18 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 19 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 20 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 21 a further embodiment of the inventive wire thread insert withredressable moving tang,

FIG. 22 a further embodiment of the inventive wire thread insert withredressable moving tang, and

FIG. 23 a further embodiment of the inventive wire thread insert withredressable moving tang.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The inventive wire thread insert 10 is wound from a wire of knownmaterial and of known cross-sectional shape. Referring to the FIGS. 3 to9 and 17-23, the wire thread insert 10 comprises a cylindrical helix 20consisting of a plurality of helically wound coils 30. The helix 20 hasa first end 22 and a second end 24. A moving tang 50 is arranged at thefirst end 22 of the cylindrical helix 20 which protrudes into theinterior of the cylindrical helix 20 in a radial plane of thecylindrical helix 20.

A moving tang 50 is connected to a first coil 32 of the cylindricalhelix 20 at its first end 22 via a bending portion 40. The moving tang50 protrudes not straight radially into the interior of the cylindricalhelix 20, as can be seen from FIGS. 3, 5, 7 and 9. Instead, the movingtang 50 has the shape of circular arc. The circular arc of the movingtang 50 has preferably the same radius as the cylindrical helix 20 sothat the moving tang 50 is permanently redressable from the interior ofthe cylindrical helix 20 into the pathway of the first coil 32. It isfurther preferred to form the circular arc of the moving tang 50 with aradius that differs at the maximum by ±10% from the radius of thecylindrical helix 20.

The bending portion 40 has the function to connect the moving tang 50with the rest of the wire thread insert 10 bendable and with tensilerigidity. Thereby it is ensured that a sufficient high torque can beapplied to the wire thread insert 10 via the moving tang 50 during theinstallation of the wire thread insert 10 into a receiving thread A of acomponent B. Based on this constructive basis, the wire thread insert 10can be drawn-in into the receiving thread A by means of the moving tang50 without that the moving tang 50 breaks.

Further, the bending portion 40 ensures that the moving tang 50 ispermanently redressable into the receiving thread A of the component Bor generally into the pathway of the first coil 32. For this purpose,the bending portion 40 has the same mechanical, thermal, chemical andgeometrical properties as the wire of the cylindrical helix 20. By meansof an appropriate installation tool (see below), the moving tang 50 isbent-out in radial direction from the interior of the cylindrical helix20 during the redressing but without that the moving tang 50 returnsafterwards elastically back into the interior of the cylindrical helix20. This condition is illustrated in FIGS. 4 and 6.

Preferably, the wire is modified in its bending portion 40 in itsbending properties compared to the wire of the cylindrical helix 20 tosupport the redressing of the moving tang 50 into the receiving thread Aor into the pathway of the first coil 32. This modification of thebending portion 40 is caused according to different embodiments of thepresent invention mechanically, geometrically, thermally, chemically orin another way.

According to another preferred embodiment, the wire of the bendingportion 40 is tapered in its cross-section compared to the wire of thecylindrical helix 20. According to one alternative, this is realisedwith a groove or notch 42, preferably a rounded or angular groove. Thetapering or groove 42 is formed such that a low groove factor arisesduring the redressing of the moving tang 50 and thus the moving tang 50does not break-off during the redressing. It is further preferred toarrange the groove 42 on the radially inner or on the radially outerside of the bending portion 40. According to another alternativeembodiment, a one-sided or a multi-sided cross-sectional tapering of thebending portion 40 takes place for 10 to 80%, preferably forapproximately 50%, compared to the wire of the cylindrical helix 20.

According to another preferred embodiment of the wire thread insert 1not shown, the groove 42 is formed as a moving groove. The moving grooveis formed and positioned such that it may enter a moving blade providedin the shape of the screw-in tool for screwing-in the wire thread insert1 into a receiving thread and that it can be locked therein by positivelocking. An example for such a moving groove is shown in FIG. 2 atreference sign 7. Due to this shape, the side of the moving groovelocated upstream in the screw-in direction of the wire thread insert 1forms an undercut at which the moving blade abuts with a positivelocking. The radially inwardly bent moving tang 50 supports theengagement of the moving blade into the moving groove. Thus, the movinggroove realises two functions at the same time. On the one hand, themoving groove allows the engagement and locking of the moving blade of ascrew-in tool for the wire thread insert. On the other hand, the movinggroove constitutes a tapering of the bending portion 40 which supports aredressing of the moving tang 50 into the receiving thread of thecomponent.

The bending portion is treated mechanically, to reduce the mechanicalresistance moment or the elastic restoring moment of the wire in thebending portion 40, for example from up to 2000 MPa to approximately 400MPa. Suitable procedures comprise notching, milling, punching, forging,grinding, polishing, cold-forming, etching, lapping to reduce thecross-section of the bending portion 40. At the same time, it must beensured that the corrosion properties in the bending portion 40 arerestored after the treatment.

According to another embodiment of the present invention, the wire ofthe bending portion 50 is modified thermally or chemically or in anotherway so that its bending strength is reduced compared to the wire of thecylindrical helix 20. Thus, for example, its strength is influenced viaa local thermal treatment of the bending portion 40 or of a section ofthe bending portion 40. In this way, the yield strength of the wire inthe bending portion 40 is reduced, for example to 20% to 90%, furtherpreferred to 20% to 40%. The thermal treatment is realised according todifferent embodiments by electrical induction, by laser irradiation orby applying another heat source.

According to another preferred embodiment of the bending portion 40, itswire is untreated, thus neither mechanically, geometrically, chemically,physically nor in any other way and corresponds in its properties to thewire of the cylindrical helix 20.

Based on the above described embodiments of the bending portion 40 andthe shape of the moving tang 50, the moving tang 50 of a wire threadinsert 10 installed in the receiving thread A of the component B may bebent-out of the interior of the cylindrical helix 20 so that thereceiving thread A with the wire thread insert 10 is true to gauge. Thismeans that a screw or a thread plug gauge is screwable into thereceiving thread A having the wire thread insert 10 using a negligiblelow additional torque or frictional moment, respectively, due to theredressed moving tang 50. The accuracy to gauge of the receiving threadA having the wire thread insert 10 is provable in that a manualscrewing-in of the thread plug gauge according to tolerance class 6H,preferably tolerance class 5H, is guaranteed.

According to different embodiments of the present invention, the movingtang 50 is formed in different lengths. In the redressed conditionaccording to FIGS. 4 and 6, the moving tang 50 extends over a circulararc A_(RZ) from 10° to 180°, preferably 30° to 120°, starting in thebending portion 40 to the free end of the moving tang 50.

Further, the bending portion 40 has a certain tang bending radius. Thesize of the tang bending radius determines at which position the movingtang 50 is arranged in the interior of the cylindrical helix 20. It ispreferred to choose the tang bending radius in the manner that themoving tang 50 and the first coil 32 include an angle α from 20° to 50°,preferably 60° to 90° (confer FIG. 5A). Alternatively to this it is alsopreferred to adjust the tang bending radius R of the moving tang 50specifically. The tang bending radius R (cf. FIG. 5B) describes theradius by means of which the moving tang 50 is radially bent inwardly.This tang bending radius R is measured for example by means of radiusgauges. The tang bending radius R has a size of 0,5 P≤R≤0,45 D_(A). Inthis equation denotes P the pitch of the wire in the helix 20 and D_(A)the outer diameter of the helix 20.

The moving tang 50 comprises further preferred at the front end of itsfree end a continuous compression face 52. The compression face 52 isformed unitary so that it is aligned in a common angle β to thelongitudinal axis L of the wire of the moving tang 50. The angle β isexemplary shown in FIG. 5. The angle β amounts to 80° to 130° to thelongitudinal axis L of the wire of the moving tang 50 within a radialplane of the cylindrical helix 20.

Referring to FIGS. 7 and 8, the moving tang 50 is formed shortercompared to FIGS. 3 and 4. Further, FIGS. 3, 4 and 7 illustrate a wirethread insert 10 whose bending portion 40 is electrically, chemically,thermally or not at all modified. In FIGS. 4 and 6, the moving tang 50is permanently redressed into the first coil 32 without springing backelastically into the interior of the cylindrical helix 20.

The present invention comprises further the component B with receivingthread A in which the above described wire thread insert 10 isinstalled. In the installed condition, the moving tang 50 is redressedor still arranged in the interior of the cylindrical helix 20.Exemplarily, FIGS. 11 and 12 show component A with installed wire threadinsert 10.

The wire thread insert 10 is installed in the receiving thread A of thecomponent B by means of an installation tool. The installation toolcomprises a rotatable mounting spindle 60 having a driving end forrotating the mounting spindle 60 and a functional end 65 for installingthe wire thread insert 10. The functional end 65 of the mounting spindle60 is shown in FIG. 9 in a preferred embodiment. On the mounting spindle60, especially on the functional end 65, the wire thread insert 10 washere already spindled or slipped thereon (step S1). To this end, themounting spindle 60 comprises at its functional end 65 an outer diameteradapted to the inner diameter of the wire thread insert 10 so that thewire thread insert 10 is screwable or placeable on the mounting spindle60.

The functional end 65 is preferably located on the front end of themounting spindle 60. It comprises a moving shoulder 70 by means of whichthe wire thread insert 10 is screwable into the receiving thread A viathe moving tang 50. Further, the functional end 65 comprises acompression blade 80 by means of which the moving tang 50 of the wirethread insert 10 is redressable. Preferably, the compression blade 80cooperates with a redress shoulder 94.

At the end of the spindling or slipping of the wire thread insert on themounting spindle 60 (step S1), the moving tang 50 locks (step S2) itselfpreferably behind the moving shoulder 70. To facilitate the locking(step S2) and to ensure a trouble-free engagement of the moving tang 50on the moving shoulder 70 an engagement slant 72 is arranged on themoving shoulder 70 (see FIGS. 9 and 10). The moving tang 50 iselastically deformed during the further screwing on the mounting spindle60 and slides on the front end over the moving shoulder 70, thecompression blade 80 as well as over the redress shoulder 90. To achievea low-drag sliding of the moving tang 50, the edges of the mentionedcontact faces at the functional end 65 of the mounting spindle 60 arebroken such that a hooking in or jamming of the moving tang isprevented. Due to the elasticity of the moving tang 50, the moving tang50 snaps behind the moving shoulder 70 of the mounting spindle 60 into atension free position and is thereby locked.

The spindled or slipped-on wire thread insert 10 is positioned at thereceiving thread A. Due to the inward winding of the first coil 30 inthe bending portion 40, an ideal entering of the wire thread insert 10into the receiving thread A is ensured. The screwing in (step S3) of thewire thread insert 10 into the receiving thread A takes place by meansof a rotating movement of the mounting spindle 60 via the mounting tool.In a wire thread insert 10 for a right hand thread, the screwing-intakes place in a clockwise direction. For a left hand thread, themounting spindle 60 is turned counter-clockwise, respectively, toinstall the wire thread insert 10.

By screwing-in the wire thread insert 10 into the receiving thread A,the moving tang 50 abuts the moving shoulder 70 of the functional end65. This ensures an ideal transmission of the torque to be applied,whereby the wire thread insert 10 is brought into the desired depthposition within the receiving thread A. For a better fixation of themoving tang 50 on the moving shoulder 70, the moving shoulder 70comprises a moving groove 74. The moving tang 50 snaps into this movinggroove 74 whereby an additional stability for the torque transmission onthe wire thread insert 10 is obtained.

The depth position of the wire thread insert 10 is adaptable via anadjustable depth stop depending from the length of the wire threadinsert 10 as well as the desired end position of the wire thread insertin the receiving thread A. After the depth position is reached, themounting spindle 60 is screwed counter-clockwise out of the wire threadinsert 10 (steps S4 to S6). Immediately after changing the rotationaldirection of the mounting spindle 60, the moving shoulder 70 isdisengaged from the moving tang 50 and the moving tang 50 is radiallybent open by the redress shoulder 90 due to its geometry (step S4). Thebent open condition obtained by the redress shoulder 90 is shown in FIG.11. In this condition, the moving tang 50 is guided between thereceiving thread A and the groove 92 of the redress shoulder.

By further rotating the mounting spindle 60 in the counter-clockwisedirection, the compression face 52 of the moving tang 50 abuts thecompression blade 80 (confer FIG. 12). For this purpose, the compressionblade 80 extends in radial direction related to the mounting spindle 60and projects over an outer diameter of the mounting spindle 60. Based onthis construction, the moving tang 50 is permanently redressable intothe receiving thread of the component B.

In case the mounting spindle 60 is rotated further in the direction ofthe arrow according to FIGS. 11 and 12, the mounting tang 50 iscompressed by the compression blade 80 via the compression face 52 (stepS5). The moving tang 50 is preferably held between the receiving threadA and the groove 92 of the redress shoulder 90 so that the moving tang50 does not give way to the compression force. Due to the clinchingforce impact of the moving tang 50 superimposed with the bending stress,a multi-axial stress condition is created in the bending portion 40. Dueto this multi-axial stress condition, the material yield strength of thewire in the bending portion is preferably clearly exceeded so that themoving tang 50 is redressed permanently into the receiving thread A orin the continuation of the first winding 32, respectively. Thereby, thefirst coil 32 is not damaged.

After the compression in step S5 is completed, the compression blade 80disengages from the compression face 52 and the mounting spindle 60 isscrewed-out or removed in another way from the wire thread insert 10.

A further preferred embodiment of the mounting spindle 60 is shown inFIG. 16. This embodiment works in them the same way as described above.In contrast to the above described mounting spindle 60, the compressionblade 80′ is arranged tangentially pivoting into the circumferentialshape of the wire thread insert to be installed. To this end, thecompression blade 80′ is arranged pivotably around the point 82.According to one embodiment, the compression blade 80′ is connected witha rotational axis which extends axially in the mounting spindle 60 andis driveable by a drive means. As the point 82 is arranged eccentricallyin relation to the front end of the mounting spindle, the radial outerend of the compression blade 80′ reaches the envelope curve of thecomponent thread during a pivoting movement. In a mounting procedure ofthe wire thread insert, the compression blade 80′ engages during theturning back of the mounting spindle 60 the compression face 52 of themoving tang 50 after the redress shoulder 90 has bent the moving tang 50outwardly. For this purpose, the compression blade 80′ is rotated fromthe position illustrated by dotted lines into the position illustratedby continuous lines (see FIG. 16). As the compression blade 80′ is rigidin the position illustrated by the continuous lines, rotating of themounting spindle 60 in the direction of the arrow compresses the movingtang 50 so that the moving tang 50 is redressed permanently.

The wire thread insert 10 is manufactured with a device which is shownin FIG. 14 according to one embodiment. A wire D to be wound issuppliable to a rotatably arranged winding spindle W via a wire supplyDZ. The winding spindle W comprises on its front end a lockingconstruction (not shown). The locking construction is formed such that acircular arc shaped curved end D₁ of the wire D to be wound is lockableon the front end of the winding spindle W for winding the wire threadinsert (step H2). Preferably, the circular arc shaped curved end D₁ ofthe wire D extends over an arc angel of 10° to 180°, preferably 30° to120°. This circular arc starts in the later bending portion or at theend of the straight section of the wire D to be wound, respectively.This circular arc ends at the free end of the circular arc shaped curvedend D₁ or at the free end of the later moving tang, respectively.

After providing the wire D to be wound with a circular arc shaped curvedend D₁ (step H1) and locking the circular arc shaped curved end D₁ atthe winding spindle W (H2), the winding spindle W winds the wire D up(step H3). By rotating the winding spindle W, the cylindrical helix 20consisting of the plurality of helically wound coils 30 is created (seeabove). The locking of the semicircular end D₁ of the wire D leads tothe forming of the moving tang 50 (see above) already at the beginningof the winding procedure.

After the wire thread insert is completely wound, the wire thread insertis spindled-off from the winding spindle W (step H4). For this purpose,the winding spindle W rotates contrary to the previously used windingdirection.

Now, the wire thread insert is only connected with the endless wire Dand has to be cut-off therefrom. With the cutting-off (step H6) of thewire thread insert, two preferred objectives are achieved. On the onehand, an upper M1 and a lower knife M2 are used for cutting-off (H6),which cut off the wire thread insert over a shear movement. In contrastto pinching-off, cutting-off (H6) creates a continuous face which formsin the wire thread insert to be formed subsequently the compression face52 at the moving tang 50 (see above).

On the other hand, the wire thread insert is cut-off with the upper M1and lower knife M2 such that a semicircular free end of the wire Dremains. For this purpose, the wire thread insert is preferably tilted(step H5) related to its longitudinal axis and compared to thelongitudinal axis of the winding spindle W before cutting-off (H6). Inthis way, the end of the wire thread insert to be cut is freelyaccessible for the knives M1 and M2.

While the cut-off wire thread insert is removed (step H7), thesemicircular end of the wire D at the front end of the winding spindle Wis locked (step H1 and H2) to wind a further wire thread insert.

The device for manufacturing the wire thread insert comprises furtherpreferably a pointing assembly with which the wire of the bendingportion 40 between the first coil 32 of the wire thread insert 10 andthe moving tang 50 is modifiable mechanically, geometrically, thermally,chemically or in another way compared to the wire of the remaining wirethread insert 10 to facilitate a redressing of the moving tang 50. Themodification of the wire in the bending portion 40 and thus also thepointing assembly are optional. The advantages related to thesemodifications of the wire in the bending portion are described above.

The pointing assembly P is arranged such that during the manufacturingof the first wire thread insert the pointing or modifying of the wire,respectively, occurs already at the position of the bending portion 40of the wire thread insert subsequently to be wound. The pointingassembly further comprises for this purpose preferably mechanicaldevices for milling, punching or the like, as discussed above. Theyapply for example a rounded groove or a tapering in the later bendingportion of the wire thread insert subsequently to be wound.

Alternatively, the pointing assembly comprises an inductor to chemicallymodify the properties of the wire in the later bending portion 40. It isfurther conceivable to provide the pointing assembly P with other heatsources or mechanical treatment devices to modify the wire in the laterbending portion 40 in a suitable way.

The invention claimed is:
 1. An installation method of a wire threadinsert having a redressable moving tang adapted to be bent back by aninstallation tool into a receiving thread of a component wherein theinstallation tool comprises the following features: a rotatable mountingspindle having a drive end for rotating the mounting spindle and afunctional end for installing the wire thread insert, wherein thefunctional end comprises a moving shoulder by which the wire threadinsert is screwable into the receiving thread via the moving tang and acompression blade by which the moving tang of the wire thread insert isredressable, wherein the compression blade extends in a radial directionand projects in the radial direction beyond an outer diameter of themounting spindle as defined by an outer radial surface of the mountingspindle so that the moving tang is permanently redressable into thereceiving thread of the component, or the compression blade is arrangedpivotably around an eccentrically arranged point related to the frontend face of the mounting spindle as defined by a rotational axisextending axially in the mounting spindle so that the compression bladeis arranged pivotable into a tangential position of the outer radialsurface of the mounting spindle and into the circumferential shape ofthe wire thread insert to be installed, so that the moving tang ispermanently redressable into the receiving thread of the component, themethod comprising the following steps: a. spindling or slipping the wirethread insert on a functional end of a mounting spindle of theinstallation tool, b. screwing-in the wire thread insert into thereceiving thread by rotating the mounting spindle in a first rotationaldirection, c. radially and outwardly bending-up of the moving tang intothe receiving thread by rotating the mounting spindle in a secondrotational direction, and d. spindling-off or removing the mountingspindle from the wire thread insert with redressed moving tang. 2.Installation method according to claim 1, comprising the further step:locking the moving tang of the wire thread insert at a moving shoulderof the functional end of the mounting spindle so that the wire threadinsert is rotatable by the mounting spindle.
 3. Installation methodaccording to claim 1, comprising the further step: bending-up radiallythe moving tang by a bending-up shoulder at the functional end of themounting spindle.
 4. Installation method according to claim 1,comprising the further step: compressing the moving tang by acompression blade of the functional end of the mounting spindle so thatthe moving tang is arranged within the receiving thread of thecomponent.
 5. Installation method according to claim 2, comprising thefurther step: bending-up radially the moving tang by a bending-upshoulder at the functional end of the mounting spindle.
 6. Installationmethod according to claim 2, comprising the further step: compressingthe moving tang by a compression blade of the functional end of themounting spindle so that the moving tang is arranged within thereceiving thread of the component.
 7. Installation method according toclaim 3, comprising the further step: compressing the moving tang by acompression blade of the functional end of the mounting spindle so thatthe moving tang is arranged within the receiving thread of thecomponent.
 8. Installation method according to claim 1, wherein the wirethread insert has the following features: a cylindrical helix having aplurality of helically wound coils of a wire, the helix having a firstand a second end, wherein a first coil provided at the first end has amoving tang projecting into an interior of the helix via a bendingportion and the moving tang is inseparably connected to the first coiland redressable from the interior of the helix via the bending portion.9. Installation method according to claim 8, the moving tang of which isredressable into the receiving thread of the component permanently. 10.Installation method according to claim 8, the moving tang of which is acircular arc, wherein a tang radius is approximately equal to a radiusof the first coil of the cylindrical helix.
 11. Installation methodaccording to claim 8, the moving tang of which has a continuous frontend compression face at its free end, which is arranged within theradial plane of the helix in an angle of 80° to 130° related to thelongitudinal axis of the wire.
 12. Installation method according toclaim 8, wherein the wire in the bending portion between the first coiland the moving tang is modified mechanically, geometrically, thermally,chemically or in another way compared to the wire of the first coil sothat a redressing of the moving tang is facilitated.
 13. Installationmethod according to claim 1, the functional end of which comprises aredressing shoulder by which the moving tang during the rotation of themounting spindle is radially outwardly movable and redressable incombination with the compression blade.
 14. Installation methodaccording to claim 1, the mounting spindle of which has an outerdiameter at the functional end so that the wire thread insert may bespindled or slipped on.
 15. Installation method according to claim 1,the compression blade of which is arranged radially and/or axiallymoveable related to the mounting spindle to engage or disengage themoving tang.